Method for treating mercaptans contained in a sour petroleum distillate

ABSTRACT

A method of treating a mercaptan-containing sour petroleum distillate which comprises contacting said distillate with a catalytic composite comprising a carrier material, a metal chelate oxidation catalyst, a substituted ammonium compound, and a linear ionic compound.

CROSS-REFERENCE TO RELATED APPLICATION

This is a division of copending application Ser. No. 169,553 filed July17, 1980, now U.S. Pat. No. 4,320,029, the teachings of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The field of art to which the claimed invention pertains is thetreatment of sour petroleum distillates or fractions, said treatmentbeing commonly referred to as sweetening. More specifically, the claimedinvention relates to a method of treating a mercaptan containing sourpetroleum distillate which comprises contacting said distillate atoxidation conditions with a catalytic composite comprising a carriermaterial, a metal chelate oxidation catalyst, a substituted ammoniumcompound, and a linear ionic compound.

2. Description of the Prior Art

Processes for the treatment of a sour petroleum distillate, wherein saiddistillate is treated, in the presence of an oxidizing agent at alkalinereaction conditions, with a supported metal phthalocyanine catalystdisposed as a fixed bed in a treating or reaction zone, have become wellknown and widely accepted in the industry. The treating process istypically designed to effect the catalytic oxidation of offensivemercaptans contained in the sour petroleum distillate with the formationof innocuous disulfides. The oxidizing agent is most often air admixedwith the sour petroleum distillate to be treated. Gasoline, includingnatural, straight run and cracked gasolines, is the most frequentlytreated sour petroleum distillate. Other sour petroleum distillatesinclude the normally gaseous petroleum fraction as well as naphtha,kerosene, jet fuel, fuel oil, lube oil, and the like.

A commonly used continuous process for treating sour petroleumdistillates entails treating the distillate in contact with a metalphthalocyanine catalyst dispersed in an aqueous caustic solution toyield a doctor sweet product. The sour distillate and thecatalyst-containing aqueous caustic solution provide a liquid-liquidsystem wherein mercaptans are converted to disulfides at the interfaceof the immiscible solutions in the presence of an oxidizingagent--usually air. Sour petroleum distillates containing moredifficultly oxidizable mercaptans are more effectively treated incontact with a metal phthalocyanine catalyst disposed on a high surfacearea adsorptive support--usually a metal phthalocyanine on an activatedcharcoal. The distillate is treated in contact with the supported metalphthalocyanine catalyst at oxidation conditions in the presence of analkaline agent. One such process is described in U.S. Pat. No.2,988,500. The oxidizing agent is most often air admixed with thedistillate to be treated, and the alkaline agent is most often anaqueous caustic solution charged continuously to the process orintermittently as required to maintain the catalyst in a caustic-wettedstate.

The prior art suggests that a way to impove the oxidation of mercaptanscontained in sour petroleum distillates is the addition of specifiedadditives to the metal phthalocyanine solutions employed in preparingthe catalytic composites. The prior art discloses that a higher activitycatalytic composite results from the use of a soluble acid amide (U.S.Pat. No. 4,098,681). A catalytic composite of improved activity has alsobeen found to result from the inclusion of a carboxylic acid in a metalphthalocyanine solution (U.S. Pat. No. 4,087,378, U.S. Pat. No.4,107,078). Other additives to the metal phthalocyanine solution whichhave been disclosed as providing a catalytic composite of higheractivity are polynuclear aromatic sulfonic acid (U.S. Pat. No.4,124,531), morpholine (U.S. Pat. No. 4,142,964), and an alkanolaminehydroxide (U.S. Pat. No. 4,159,964).

The prior art does not, however, suggest that a sweetening process canbe effected in the presence of a catalytic composite comprising acarrier material, a metal chelate oxidation catalyst, a substitutedammonium compound, and a linear ionic compound.

It is a broad objective of my invention to provide a novel process fortreating a mercaptan-containing petroleum distillate.

In brief summary, my invention is, in one embodiment, a sweeteningprocess, comprising contacting, in the presence of an alkaline reagentat oxidation conditions, a mercaptan-containing sour petroleumdistillate with a catalytic composite comprising a carrier material, ametal chelate oxidation catalyst, a linear ionic compound, and asubstituted ammonium compound.

A more specific embodiment of my invention comprises the process recitedin the preceding paragraph wherein the linear ionic compound containsfrom about 9 to about 24 carbon atoms and has an anionic portion,wherein said anionic portion is selected from the group consisting ofsulfonate, sulfate and carboxylate and the substituted ammonium compoundis represented by the structural formula: ##STR1## where R is ahydrocarbon radical containing up to about 20 carbon atoms and selectedfrom the group consisting of alkyl, cycloalkyl, aryl, alkaryl andaralkyl, R₁ is a substantially straight-chain alkyl radical containingfrom 5 to about 20 carbon atoms, and X is an anion selected from thegroup consisting of halide, nitrate, nitrite, sulfate, phosphate,acetate, citrate, tartrate and hydroxide.

One of the preferred embodiments of my invention comprises the processas recited above wherein the substituted ammonium compound isdimethylbenzylalkylammonium chloride, and the metal chelate oxidationcatalyst is a cobalt phthalocyanine sulfonate.

Other objects and embodiments will become apparent in the followingdetailed description.

SUMMARY OF THE INVENTION

It is a broad objective of my invention to produce a novel catalyst ofincreased activity and stability compared with catalyst produced byprior art methods.

Another objective is to provide a process for treating amercaptan-containing petroleum distillate in which said novel catalystis used.

In brief summary, I have found that a catalyst especially useful in thetreatment of sour petroleum distillates or fractions may be prepared bycontacting a carrier material with a solution of a metal chelate, with alinear ionic compound, and with a substituted ammonium compound.

A more specific embodiment of the invention comprises the method recitedin the preceding paragraph wherein the substituted ammonium compound isrepresented by the structural formula: ##STR2## wherein R is ahydrocarbon radical containing up to about 20 carbon atoms and selectedfrom the group consisting of alkyl, cycloalkyl, aryl, alkaryl andaralkyl, R₁ is a substantially straight-chain alkyl radical containingfrom about 5 to about 20 carbon atoms, and X is an anion selected fromthe group consisting of halide, nitrate, nitrite, sulfate, phosphate,acetate, citrate, tartrate and hydroxide.

Another embodiment of this invention is a catalytic composite comprisinga carrier material, a metal chelate, a linear ionic compound, and asubstituted ammonium compound.

One of the preferred embodiments of the invention is a method comprisingcontacting an activated charcoal adsorptive support with a cobaltphthalocyanine sulfonate solution, with a saturated linear ioniccompound having from about 9 to about 24 carbon atoms, and with adimethylbenzylalkylammonium chloride.

Another of the preferred embodiments of the invention is a methodcomprising contacting, in the presence of an alkaline reagent atoxidation conditions, a mercaptan-containing sour petroleum distillatewith a catalytic composite prepared as set forth in the precedingparagraph.

Other objects and embodiments will become apparent in the followingdetailed description.

DESCRIPTION OF THE INVENTION

The carrier material employed in the catalytic composite used in theprocess of the invention herein contemplated includes the various andwell-known adsorbent materials in general use as catalyst supports.Preferred carrier materials include the various charcoals produced bythe destructive distillation of wood, peat, lignite, nut shells, bones,and other carbonaceous matter, and preferably such charcoals as havebeen treated, or chemically treated, or both, to form a highly porousparticle structure of increased adsorbent capacity, and generallydefined as activated charcoal. Said carrier materials also include thenaturally occurring clays and silicates, for example, diatomaceousearth, fuller's earth, kieselguhr, attapulgus clay, feldspar,montmorillonite, halloysite, kaolin, and the like, and also thenaturally occurring or synthetically prepared refractory inorganicoxides such as alumina, silica, zirconia, thoria, boria, etc., orcombinations thereof, like silica-alumina, silica-zirconia,alumina-zirconia, etc. Any particular carrier material is selected withregard to its stability under conditions of its intended use. Forexample, in the treatment of a sour petroleum distillate, the carriermaterial should be insoluble in, and otherwise inert to, the petroleumdistillate at alkaline conditions typically existing in the treatingzone. Charcoal, and particularly activated charcoal, is preferredbecause of its capacity for metal phthalocyanine and because of itsstability under treating conditions. However, it should be observed thatthe method of this invention is also applicable to the preparation of ametal chelate composited with any of the other well-known carriermaterials, particularly the refractory inorganic oxides.

The metal chelate employed in the practice of this invention can be anyof the various metal chelates known to the treating art as effective tocatalyze the oxidation of mercaptans contained in a sour petroleumdistillate with the formation of polysulfide oxidation products. Saidmetal chelates include the metal compounds of tetrapyridinoporphyrazinedescribed in U.S. Pat. No. 3,980,582, e.g. cobalttetrapyridinoporphyrazine; porphyrin and metaloporphyrin catalysts asdescribed in U.S. Pat. No. 2,966,453, e.g. cobalt corrin sulfonate;chelate organometallic catalysts such as described in U.S. Pat. No.2,918,426, e.g. the condensation product of an aminophenol and a metalof Group VIII; and the like. It is particularly preferred that metalphthalocyanines be used in the practice of the present invention.

The metal phthalocyanines which can be employed to catalyze theoxidation of mercaptans contained in sour petroleum distillatesgenerally include magnesium phthalocyanine, titanium phthalocyanine,hafnium phthalocyanine, vanadium phthalocyanine, tantalumphthalocyanine, molybdenum phthalocyanine, manganese phthalocyanine,iron phthalocyanine, cobalt phthalocyanine, nickel phthalocyanine,platinum phthalocyanine, palladium phthalocyanine, copperphthalocyanine, silver phthalocyanine, zinc phthalocyanine, tinphthalocyanine, and the like. Cobalt phthalocyanine and vanadiumphthalocyanine are particularly preferred. The metal phthalocyanine ismore frequently employed as a derivative thereof, the commerciallyavailable sulfonated derivatives, e.g. cobalt phthalocyaninemonosulfonate, cobalt phthalocyanine disulfonate or a mixture thereofbeing particularly preferred. The sulfonated derivatives may beprepared, for example, by reacting cobalt, vanadium, or other metalphthalocyanine with fuming sulfuric acid. While the sulfonatedderivatives are preferred, it is understood that other derivatives,particularly the carboxylated derivatives, may be employed. Thecarboxylated derivatives are readily prepared by the action oftrichloroacetic acid on the metal phthalocyanine.

The substituted ammonium compounds which can be employed in thisinvention are those compounds having four hydrocarbon radicals whereineach of said radicals comprises from about 1 to about 20 carbon atoms.Such substituted ammonium compounds include tetramethylammoniumhydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide,tetrabutylammmonium hydroxide, trimethylethylammonium hydroxide,trimethylpropylammonium hydroxide, trimethylbutylammonium hydroxide,dimethyldiethylammonium hydroxide, dimethyldipropylammonium hydroxide,dimethyldibutylammonium hydroxide, methyltriethylammonium hydroxide,methyltripropylammonium hydroxide, methyltributylammonium hydroxide,phenyltrimethylammonium hydroxide, phenyltriethylammonium hydroxide,phenyltripropylammonium hydroxide, phenyltributylammonium hydroxide,benzyltrimethylammonium hydroxide, benzyltriethylammonium hydroxide,benzyltripropylammonium hydroxide, benzyltributylammonium hydroxide,diphenyldimethylammonium hydroxide, diphenyldiethylammonium hydroxide,diphenyldipropylammonium hydroxide, diphenyldibutylammonium hydroxide,dibenzyldimethylammonium hydroxide, dibenzyldiethylammonium hydroxide,dibenzyldipropylammonium hydroxide, dibenzyldibutylammonium hydroxide,triphenylmethylammonium hydroxide, triphenylethylammonium hydroxide,triphenylpropylammonium hydroxide, triphenylbutylammonium hydroxide, andthe like. Suitable anionic constituents include, in addition to thehydroxide ion, chloride, nitrate, nitrite, sulfate, phosphate, acetate,citrate, tartrate, and the like.

A preferred class of substituted ammonium compounds is represented bythe structural formula: ##STR3## wherein R is a hydrocarbon radicalcontaining up to about 20 carbon atoms and selected from the groupconsisting of alkyl, cycloalkyl, aryl, alkaryl and aralkyl, R₁ is asubstantially straight chain alkyl radical containing from about 5 toabout 20 carbon atoms, and X is an anion, for example, halide,hydroxide, nitrate, nitrite, sulfate, phosphate, acetate, citrate,tartrate, and the like. R₁ is preferably an alkyl radical containingfrom about 12 to about 18 carbon atoms, and X is preferably a halide orhydroxide. Especially preferred is a substituted ammonium hydroxide.Suitably substituted ammonium halides are described in U.S. Pat. No.4,124,493. The particularly preferred substituted ammonium halide is adimethylbenzylalkylammonium chloride. Substituted ammonium hydroxideswhich can give advantageous results include the hydroxides of thesubstituted ammonium halides listed in U.S. Pat. No. 4,124,493. Theparticularly preferred substituted ammonium hydroxide isdimethylbenzylalkylammonium hydroxide.

Particularly preferred substituted ammonium compounds are thoserepresented by the structural formula set forth in the precedingparagraph wherein one of the R radicals is selected from the groupconsisting of aryl, aralkyl, and alkaryl. Especially preferred aresubstituted ammonium compounds wherein the R₁ straight chain alkylradical contains from about 12 to about 18 carbon atoms, wherein one ofthe R groups is a benzyl radical, and wherein X is an hydroxide ion.Particularly preferred substituted ammonium hydroxides include thoselisted in U.S. Pat. No. 4,156,641.

The linear ionic compounds of this invention comprise straight chaincompounds which dissociate to some degree in aqueous solution intocationic and anionic constituents. The anionic constituent preferablycomprises an unbranched hydrocarbon having from about 9 to about 24carbon atoms. The anionic constituent more preferably comprises asubstantially saturated unbranched hydrocarbon having from about 9 toabout 24 carbon atoms. It is especially preferred that the anionicconstituent also comprise a sulfonate group, a sulfate group, or acarboxylate group. The cationic constituent may be any convenientcation. The linear ionic compound selected should be sufficientlysoluble in aqueous solution to permit the formation of an aqueoussolution comprising the selected quaternary ammonium compound in aconcentration of from about 0.01 wt. % to about 10 wt. % and theselected linear ionic compound in a concentration of from about 0.001wt. % to about 10 wt. %. The preferred cationic constituents are thealkali metals and ammonium. Especially preferred is sodium.

Representative of saturated linear ionic compounds which can producesatisfactory results in this invention are sodium nonyl sulfate, sodiumnonyl sulfonate, sodium nonyl carboxylate, sodium decyl sulfate, sodiumdecyl sulfonate, sodium decyl carboxylate, sodium undecyl sulfate,sodium undecyl sulfonate, sodium undecyl carboxylate, sodium dodecylsulfate, sodium dodecyl sulfonate, sodium dodecyl carboxylate, sodiumtridecyl sulfate, sodium tridecyl sulfonate, sodium tridecylcarboxylate, sodium tetradecyl sulfate, sodium tetradecyl sulfonate,sodium tetradecyl carboxylate, sodium pentadecyl sulfate, sodiumpentadecyl sulfonate, sodium pentacecyl carboxylate, sodium hexadecylsulfate, sodium hexadecyl sulfonate, sodium hexadecyl carboxylate,sodium heptadecyl sulfate, sodium heptadecyl sulfonate, sodiumheptadecyl carboxylate, sodium octadecyl sulfate, sodium octadecylsulfonate, sodium octadecyl carboxylate, sodium nonadecyl sulfate,sodium nonadecyl sulfonate, sodium nonadecyl carboxylate, sodium eicosylsulfate, sodium eicosyl sulfonate, sodium eicosyl carboxylate, sodiumheneicosyl sulfate, sodium heneicosyl sulfonate, sodium heneicosylcarboxylate, sodium docosyl sulfate, sodium docosyl sulfonate, sodiumdocosyl carboxylate, sodium tricosyl sulfate, sodium tricosyl sulfonate,sodium tricosyl carboxylate, sodium tetracosyl sulfate, sodiumtetracosyl sulfonate, and sodium tetracosyl carboxylate. As indicatedabove, cationic constituents such as ammonium and alkali metals otherthan sodium can provide satisfactory results. The preferred ioniccompound is sodium dodecyl sulfate, commonly known as sodium laurylsulfate.

Representative of unsaturated linear ionic compounds which can producesatisfactory results in the method of this invention are sodium nonenylsulfate, sodium nonynl sulfate, sodium nonadienyl sulfate, sodiumdecenyl sulfate, sodium decynl sulfate, sodium decadienyl sulfate,sodium undecenyl sulfate, sodium undecynl sulfate, sodium undecadienylsulfate, sodium dodecenyl sulfate, sodium dodecynl sulfate, sodiumdodecadienyl sulfate, sodium tridecenyl sulfate, sodium tridecynlsulfate, sodium tridecadienyl sulfate, sodium tetradecenyl sulfate,sodium tetradecynl sulfate, sodium tetradienyl sulfate, sodiumpentadecenyl sulfate, sodium pentadecynl sulfate, sodium pentadienylsulfate, sodium hexadecenyl sulfate, sodium hexadecynl sulfate, sodiumhexadienyl sulfate, sodium heptadecenyl sulfate, sodium heptadecynlsulfate, sodium heptadienyl sulfate, sodium octadecenyl sulfate, sodiumoctadecynl sulfate, sodium octadienyl sulfate, sodium nonadecenylsulfate, sodium nonadecynl sulfate, sodium nonadienyl sulfate, sodiumeicosadecenyl sulfate, sodium eicosadecynl sulfate, sodium eicosadienylsulfate, sodium heneicosadecenyl sulfate, sodium heneicosadecynlsulfate, sodium heneicosadienyl sulfate, sodium docosadecnyl sulfate,sodium docosadecynl sulfate, sodium docosadienyl sulfate, sodiumtricosadecenyl sulfate, sodium tricosadecynl sulfate, sodiumtricosadienyl sulfate, sodium tetracosadecenyl sulfate, sodiumtetracosadecynl sulfate, and sodium tetracosadienyl sulfate. Otherunsaturated linear ionic compounds which can produce satisfactoryresults include the sulfonate and carboxylate analogues of the foregoingsulfates. Cationic constituents such as ammonium and alkali metals otherthan sodium can provide satisfactory results.

The linear ionic compounds are easily prepared by well-known methodsfrom several precursors, including alcohols, acids, and olefins. Forexample, a linear carboxylate salt can be prepared from the analogouscarboxylic acid, which itself is commonly prepared from animal andvegetable fats. Thus sodium laurate is formed by the reaction of lauricacid and sodium hydroxide. Linear sulfates can be prepared by thereaction of sulfuric acid with the corresponding olefin or alcohol.Thus, lauryl alcohol reacts with sulfuric acid to form lauryl hydrogensulfate, which can be neutralized with sodium hydroxide to form sodiumlauryl sulfate. Similarly, the reaction of the corresponding olefin withsulfuric acid produces the hydrogen sulfate, which can be neutralized tothe sodium sulfate compound. The sulfonate can be prepared by thereaction of sulfuric acid with the corresponding alkane, to produce asulfonic acid which can be neutralized to a sulfonate salt.Alternatively, an alkyl sulfonic acid can be neutralized with sodiumhydroxide to form the corresponding sodium alkyl sonfonate. Stillanother alternative is the sulfonation of an alkyl halide to form thedesired compound.

As stated above, the method of preparation of this invention comprisescontacting a carrier material with a solution of a metal chelate, with alinear ionic compound, and with a substituted ammonium compound. Thecontacting can be performed sequentially in any order or concurrently.If the contacting is performed concurrently, the metal chelate, linearionic compound, and substituted ammonium compound are disposed in acommon solution, and the carrier material contacted with that solutionas discussed below. It is preferred that the common solution comprise anaqueous solution of the metal chelate, linear ionic compound, andsubstituted ammonium compound. It is especially preferred that theaqueous solution comprise an aqueous solution of ammonium hydroxide. Itis preferred that the metal chelate be in a concentration of from about0.1 wt. % to about 10 wt. % of the solution, that the linear ioniccompound be in a concentration of from about 0.001 wt. % to about 10 wt.% of the solution, and that the substituted ammonium compound be in aconcentration of from about 0.01 wt. % to about 10 wt. % of thesolution. It is also preferred that the solution comprise from about 0.1wt. % to about 5 wt. % sodium hydroxide.

The contacting of the carrier material with the metal chelate,substituted ammonium compound, and linear ionic compound can beperformed concurrently by use of a common solution or sequentially byuse of separate solutions. Thus, one embodiment of the method of thisinvention is a two-step process wherein the carrier material iscontacted with a first solution of a metal chelate, and is thereaftercontacted with a second solution of a linear ionic compound and asubstituted ammonium compound. Another embodiment of the method of thisinvention is a single-step process wherein the carrier material iscontacted with a common solution of a metal chelate, a substitutedammonium compound, and a linear ionic compound. In the preferredembodiment of the method of preparation of this invention, the carriermaterial is contacted with a first solution of a metal chelate and alinear ionic compound, and is thereafter contacted with a secondsolution of a substituted ammonium compound.

It is preferred that the solutions comprise aqueous solutions. It isespecially preferred that the solution of metal chelate comprise anaqueous solution of from about 0.1 wt. % to about 5 wt. % sodiumhydroxide. It is preferred that the metal chelate comprise from about0.1 wt. % to about 10 wt. % of the solution in which it is present. Itis preferred that the linear ionic compound comprise from about 0.001wt. % to about 10 wt. % of the solution in which it is present. It ispreferred that the substituted ammonium compound comprise from about0.01 wt. % to about 10 wt. % of the solution in which it is present.

In the practice of the method of preparation of this invention it ispreferred that the contacting of the carrier material with thesubstituted ammonium compound be performed at a temperature aboveambient temperature and below the temperature of thermal decompositionof the substituted ammonium compound. It is especially preferred toconduct the contacting at a temperature of from about 55° C. to about110° C. While the mechanism of activation is not completely understood,it is believed that the advantageous results arising from the method ofthis invention are a result in part of the interaction of the quaternaryammonium compound and linear ionic compound with the metal chelate. Itis further believed that conducting the contacting at a temperaturewithin the range hereinabove specified facilitates that interaction.

The amount of metal chelate, linear ionic compound, and substitutedammonium compound relative to the amount of carrier material in thecatalytic composite of this invention can vary widely and still yieldadvantageous results. Advantageous results can be achieved when theamount of metal chelate is up to about 25 wt. % of the amount of carriermaterial. It is preferred that the amount of metal chelate be from about0.1 wt. % to about 10 wt. % of the amount of carrier material.Advantageous results can be achieved when the amount of substitutedammonium compound is from about 0.1 wt. % to about 10 wt. % of theamount of carrier material. The amount of linear ionic compound shouldbe from about 0.01 wt. % to about 10 wt. % of the amount of carriermaterial.

The linear ionic compound, the substituted ammonium compound, and themetal chelate components can be disposed on the carrier material in anyconventional or otherwise convenient manner. Said components can bedisposed on the carrier material simultaneously from a common solutionor dispersion thereof, or separately and in any desired sequence. Thedisposition process can be effected utilizing conventional techniqueswhereby the carrier material in the form of spheres, pills, pellets,granules or other particles of uniform or irregular size or shape, issoaked, suspended, dipped one or more times, or otherwise immersed in asolution or dispersion to dispose a given quantity of the linear ioniccompound, substituted ammonium compound, and metal chelate componentsthereon. One preferred method involves the use of a steam-jacketedrotary dryer. The carrier material is immersed in the solution ordispersion contained in the dryer and the carrier material is tumbledtherein by the rotating motion of the dryer. Evaporation of the solutionin contact with the tumbling carrier material is expedited by applyingsteam to the dryer jacket. In any case, the resulting composite isallowed to dry under ambient temperature conditions, or dried at anelevated temperature in an oven, or in a flow of hot gases, or in anyother suitable manner.

An alternative and convenient method for disposing the linear ioniccompound, substituted ammonium compound, and metal chelate components onthe carrier material comprises predisposing the carrier material in asour petroleum distillate treating zone or chamber as a fixed bed andpassing the linear ionic compound, metal chelate and substitutedammonium compound solutions or dispersions through the bed in order toform the catalytic composite in situ. This method allows the solutionsor dispersions to be recycled one or more times to achieve a desiredconcentration of the linear ionic compound, substituted ammoniumcompound, and metal chelate components on the carrier material. In stillanother alternative method, the carrier material may be predisposed insaid treating zone or chamber, and the zone or chamber thereafter filledwith the solutions or dispersions to soak the support for apredetermined period.

Treatment of sour petroleum distillates in contact with the catalyticcomposite of this invention is performed in the presence of an alkalineagent and an oxidizing agent. The catalytic composite is initiallysaturated with an alkaline agent, and an alkaline agent thereafterpassed in contact with the catalyst bed, continuously or intermittentlyas required, admixed with the sour petroleum distillate. Any suitablealkaline agent may be employed. An alkali metal hydroxide in aqueoussolution, e.g. sodium hydroxide in aqueous solution, is most oftenemployed. The solution may further comprise a solubilizer to promotemercaptan solubility, e.g. alcohol, and especially methanol, ethanol,n-propanol, isopropanol, etc., and also phenols, cresols, and the like.The solubilizer, when employed, is preferably methanol, and the alkalinesolution may suitably comprise from about 2 to about 100 vol. % thereof.Sodium hydroxide and potassium hydroxide constitute the preferredalkaline agents. Others including lithium hydroxide, rubidium hydroxideand cesium hydroxide are also suitably employed.

The method of treating of this invention can be effected in accordancewith prior art treating conditions. The process is usually effected atambient temperature conditions, although higher temperatures up to about105° C. are suitably employed. Pressures of up to about 1,000 psi ormore are operable, although atmospheric or substantially atmosphericpressures are entirely suitable. Contact times equivalent to a liquidhourly space velocity of from about 0.5 to about 10 or more areeffective to achieve a desired reduction in the mercaptan content of asour petroleum distillate, an optimum contact time being dependent onthe size of the treating zone, the quantity of catalyst containedtherein, and the character of the distillate being treated.

As previously stated, sweetening of the sour petroleum distillate iseffected by oxidizing the mercaptan content thereof to disulfides.Accordingly, the process is effected in the presence of an oxidizingagent, preferably air, although oxygen or other oxygen-containing gasmay be employed. In fixed bed treating operations, the sour petroleumdistillates may be passed upwardly or downwardly through the catalyticcomposite. The sour petroleum distillate may contain sufficiententrained air, but generally added air is admixed with the distillateand charged to the treating zone concurrently therewith. In some cases,it may be of advantage to charge the air separately to the treating zoneand countercurrent to the distillate separately charged thereto.

As heretofore mentioned, the linear ionic compound, substituted ammoniumcompound, and metal chelate components of the catalytic composite ofthis invention are readily disposed on the carrier material. Thus, anyof the said components which may in time be leached from the carriermaterial and carried away in the reactant stream can be easily restoredto the catalytic composite in situ by introducing either or any of saidcomponents to the sweetening process, for example, in admixture with thedistillate being treated to be disposed on the solid adsorbent supportin the treating zone.

The following examples are presented in illustration of preferredembodiments of this invention and are not intended as undue limitationson the generally broad scope of the invention as set out in the appendedclaims.

EXAMPLE I

This example illustrates a preferred embodiment of the catalyticcomposite of this invention and the method of preparation of thisinvention. A solution is prepared by mixing together 0.2 grams ofcommercial grade (about 85% purity) monosulfonated cobalt,phthalocyanine, 0.05 grams of sodium lauryl sulfate, 0.25 grams of mixedbenzyldimethylalkylammonium hydroxides, 1 cc of 27 wt. % aqueousammonia, and sufficient deionized water to form 125 cc of solution.About 100 cc of 10×30 mesh activated charcoal particles is immersed inthe solution in a rotary evaporator, and tumbled therein for about 1hour by the rotating motion of the evaporator. Steam is thereafterapplied to the evaporator jacket and the solution is evaporated todryness in contact with the charcoal particles.

EXAMPLE II

In this example, illustrating another embodiment of this invention, thecarrier material used was a catalytic composite which had beensubstantially deactivated in a kerosene treating operation. Thedeactivated catalytic composite retained some ability to convertmercaptan sulfur to disulfides. However, the activity of the catalyticcomposite was very low, being insufficient to yield an acceptablekerosene product. The catalyst originally consisted of about 0.5 wt. %cobalt pthalocyanine monosulfonate and about 18 wt. % quaternaryammonium chloride, disposed on 10×30 mesh activated charcoal particlesof an apparent bulk density of about 0.25 gm/cc.

The deactivated composite was disposed as a fixed bed in a verticaltube, and flushed with about 600 cc of water at about 100° C. to removegum and other contaminants. Thereafter, 125 cc of a solution comprising0.15 gm of commercial grade (about 85% purity) monosulfonated cobaltphthalocyanine, 0.05 gm of sodium lauryl sulfate, 1 cc of 27 wt. %aqueous ammonia, and the balance deionized water, was charged down-flowthrough the catalyst bed, and recycled until it lost substantially allof its color. Thereafter, about 600 cc of a solution comprising 0.25 gmsof mixed benzyldimethylalkylammonium hydroxides, wherein the alkylsubstituent was a straight chain C₁₂ -C₁₈ alkyl substituent, in water ata temperature of about 100° C., was charged down-flow through thecatalyst bed. The catalyst bed was wetted with about 10 cc of a 7 wt. %aqueous caustic solution, 10 cc of said solution being substantiallycharged to the catalyst bed at about 12 hour intervals admixed with thekerosene charged thereto.

The catalytic composite was evaluated with respect to a sour kerosenefraction having an end-boiling point of 486° F. and containing 873 ppmby weight mercaptan sulfur. The kerosene was charged down-flow through100 cc of the catalytic composite disposed as a fixed bed in a verticaltubular reactor, the kerosene being charged at a liquid hourly spacevelocity of about 0.5 under 45 psig of air--sufficient to provide about1.5 times the stoichiometric amount of oxygen required to oxidize themercaptans contained in the kerosene. The kerosene was analyzed formercaptan content periodically over a period of 200 hours on stream.During that 200 hour period the mercaptan content of the treatedkerosene stream averaged about 3 ppm by weight. At the end of the 200hour period the mercaptan content of the treated kerosene was about 5ppm by weight. The deactivated catalytic composite which served as acarrier in this example has yielded a kerosene product of about 40 ppmby weight mercaptan.

It is believed that the deactivated catalytic composite which served asa carrier material in this example had been substantially depleted ofall quaternary ammonium chloride, and a substantial portion of itsoriginal cobalt phthalocyanine monosulfonate constituent. It is believedthat the deactivated catalytic composite contained no activatingconstituents other than trace amounts of cobalt phthalocyaninemonosulfonate. Therefore, it is believed that the results of the run ofthis Example II are substantially similar to results which would havebeen obtained had an activated charcoal been used as a carrier insteadof the carrier material used in this example.

I claim as my invention:
 1. A method of treating a mercaptan-containingsour petroleum distillate which comprises contacting said distillate atoxidation conditions with a catalytic composite comprising a carriermaterial, a metal chelate oxidation catalyst, a substituted ammoniumcompound, and a linear ionic compound containing from about 9 to about24 carbon atoms and having an anionic portion, wherein said anionicportion is selected from the group consisting of sulfonate, sulfate andcarboxylate, said substituted ammonium compound being represented by thestructural formula: ##STR4## where R is a hydrocarbon radical containingup to about 20 carbon atoms and selected from the group consisting ofalkyl, cycloalkyl, aryl, alkaryl and aralkyl, R₁ is a substantiallystraight-chain alkyl radical containing from about 5 to about 20 carbonatoms, and X is an anion selected from the group consisting of halide,nitrate, nitrite, sulfate, phosphate, acetate, citrate, tartrate andhydroxide.
 2. The method of claim 1 wherein one of the R groups of saidsubstituted ammonium compound is selected from the group consisting ofaryl, aralkyl, and alkaryl.
 3. The method of claim 1 wherein saidsubstituted ammonium compound is a benzyldimethylalkylammonium hydroxidewherein the alkyl substituent is a substantially straight-chain alkylradical containing from about 12 to about 18 carbon atoms.
 4. The methodof claim 1 wherein said linear ionic compound possesses a cationicportion and wherein said portion is selected from the group consistingof alkali metals and ammonium.
 5. The method of claim 3 wherein saidlinear ionic compound is selected from the group consisting of sodiumundecyl, sulfate, sodium dodecyl sulfate, and sodium tridecyl sulfate.6. The method of claim 1 wherein said carrier material is an activatedcharcoal.
 7. The method of claim 1 wherein said metal chelate oxidationcatalyst is a metal phthalocyanine.
 8. The method of claim 1 whereinsaid metal chelate oxidation catalyst is a cobalt phthalocyanine.
 9. Themethod of claim 1 wherein said metal chelate oxidation catalyst is acobalt phthalocyanine sulfonate.
 10. The method of claim 1 wherein saidcomposite comprises from about 0.01 wt. % to about 10 wt. % substitutedammonium compound, and from about 0.001 wt. % to about 10 wt. % linearionic compound.